JP4130676B2 - Compressor oil leveling device and refrigerator - Google Patents

Description

  The present invention relates to a compressor oil leveling device that equalizes refrigerating machine oil among compressors of a plurality of outdoor units, and a refrigerator having a compressor oil leveling device.

When a refrigerant is circulated using a plurality of compressors in a refrigerator, the refrigeration oil becomes uneven among the compressors, and the refrigeration oil for a specific compressor may be insufficient. In order to eliminate the uneven state of the refrigerating machine oil in this way, some conventional refrigerating machines are provided with a device for balancing the refrigerating machine oil between the compressors (see, for example, Patent Document 1). This type of refrigerator has an oil level detector that detects the oil level of the refrigeration oil in the compressor, and when the oil level detector detects a shortage of refrigeration oil, the compressor is stopped to store the refrigeration oil storage unit. Reduce the pressure. Furthermore, the oil level detector detects a compressor that stores extra refrigeration oil, operates the compressor, and increases the pressure in the reservoir. The open / close valve of the connecting pipe that connects the reservoirs of the plurality of compressors is controlled to open and close to move the refrigerating machine oil from the compressor having a high pressure to the compressor having a low pressure. The compressor oil in the compressor with high pressure decreases, and the compressor oil in the compressor with low pressure increases accordingly.
JP 2000-220892 A

Thus, the conventional refrigerator is expensive because the oil level detector is provided in all the compressors and the on-off valve is controlled based on the detection result of the oil level detector. Moreover, although the differential pressure between the storage parts of a some compressor is utilized for the movement of refrigerating machine oil, this differential pressure is formed by stopping the compressor which runs short of refrigerating machine oil. However, if the compressor is stopped for oil leveling, the cooling capacity and the heating capacity will decrease during that time.
The present invention has been made in view of such circumstances, and an object of the present invention is to stably equalize refrigerating machine oil between outdoor units with a simple configuration.

  The present invention that solves the above problems connects a plurality of outdoor units and indoor units with a collecting gas pipe and a collecting liquid pipe, and causes a compressor mounted on the outdoor unit to suck refrigerant from a suction pipe, thereby adding the refrigerant. A compressor oil leveling device that is used in a refrigerator that circulates a refrigerant by discharging after being compressed, and that keeps refrigeration oil evenly between the compressors, and is a gas-liquid connected to a high-pressure vessel of the compressor The gas-liquid separation means has a first outflow end for mainly flowing out the refrigerating machine oil, and when the gas-liquid separation means is filled with the refrigerating machine oil by mainly flowing out the gas, the refrigerating machine oil A second outflow end for flowing out the refrigerant, and the first outflow end is connected to a portion of the suction pipe for supplying a refrigerant to the compressor via the first pressure reducing means, and the second outflow end is connected to the second outflow end. An oil leveling pipe is connected to the oil leveling pipe, and the second pressure reducing means is provided in the path. The inter-unit oil leveling pipes are connected to the unit oil leveling pipes, and the inter-unit oil leveling pipes are branched into two connection pipes after the oil leveling pipes of each of the plurality of outdoor units are connected. A pipe is connected to the collecting gas pipe via a first flow path switching means, and a second branch pipe is connected to the collecting liquid pipe via the second flow path switching means. A compressor oil leveling device was used.

  In this compressor oil leveling device, when the oil level of the refrigerating machine oil of the compressor is lower than the connection height of the pipe connected to the inflow end of the gas-liquid separation means, the refrigerant mixed with the mist of the refrigerating machine oil is mixed. It flows into the gas-liquid separation means, and the mist of the refrigerator oil is separated from the refrigerant by the gas-liquid separation means and returned to the original compressor. On the other hand, when the oil level of the refrigerating machine oil of the compressor is higher than the connection height of the pipe, the refrigerating machine oil flows into the gas-liquid separating means and the refrigerating machine oil also flows out into the oil equalizing pipe. This refrigerating machine oil flows into the gas pipe or the liquid pipe from the oil leveling pipe or the inter-unit oil leveling pipe through the first or second flow path switching means, and is sucked into the compressor through the gas pipe or the liquid pipe. Is done.

  According to the present invention, refrigeration oil does not flow out of a compressor with a small amount of refrigeration oil, and refrigeration oil flows out of a compressor with a large amount of refrigeration oil into other compressors including other outdoor units. Since it is distributed, in the refrigerator having a plurality of outdoor units, the amount of compressor oil in the compressor can be maintained at a predetermined amount. Moreover, the amount of refrigerating machine oil of the plurality of compressors can be maintained at a predetermined amount without performing special operation control as in the prior art. Therefore, it is possible to always achieve stable operation with a simple configuration.

The best mode for carrying out the invention will be described in detail with reference to the drawings.
FIG. 1 shows a configuration of a refrigerator according to the present embodiment. In the refrigerator 1, three outdoor units 2 to 4 are connected in parallel to a collecting gas pipe 5 (gas pipe) and a collecting liquid pipe 6 (liquid pipe), and the collecting gas pipe 5 and the collecting liquid pipe 6 include A plurality of indoor units 7 used indoors are connected in parallel. Such a refrigerator 1 may be called an outdoor multi air conditioner. In addition, the number of outdoor units 2-4 and the number of indoor units 7 are not limited to what was illustrated.

  A first compressor 10 and a second compressor 11 are mounted on the outdoor unit 2. The first and second compressors 10 and 11 are high-pressure shell type compressors, and a discharge pipe 14 is connected to each discharge port. The discharge pipe 14 is connected to the first port 16 </ b> A of the four-way valve 16 through the oil separator 15 after merging into one. The four-way valve 16 has four ports. When the first port 16A and the second port 16B are connected, the third port 16C and the fourth port 16D are connected, and the first port 16A and When the fourth port 16D is connected, the second port 16B and the third port 16C can be switched so as to be connected. The second port 16B of the four-way valve 16 is connected to the liquid pipe 6A via the outdoor heat exchanger 17. The liquid pipe 6A is connected to the collecting liquid pipe 6A, and an outdoor decompression device 18 is provided in the pipe line. The collecting liquid pipe 6 is connected to the liquid pipe 6A from each of the outdoor units 2 to 3, and is branched into three liquid pipes 6B on the indoor unit 7 side. Are connected one by one to the indoor decompression device 20 of each indoor unit 7.

  In the indoor unit 7, an indoor decompression device 20 and an indoor heat exchanger 21 are connected in series, and the gas pipe 5 </ b> B of the collective gas pipe 5 is connected to the indoor heat exchanger 21.

  The gas pipe 5 </ b> B is connected to the collective gas pipe 5. The collective gas pipe 5 is branched into three gas pipes 5A on the outdoor unit 2 side, and these gas pipes 5A are drawn into the outdoor units 2 to 3 one by one, into the fourth port 16D of the four-way valve 16. It is connected. A suction pipe 23 is connected to the third port 16C of the four-way valve 16. The suction pipe 23 is a pipe through which the refrigerant sucked into the first and second compressors 10 and 11 flows after heat exchange. After the oil return pipe 24 from the oil separator 15 is joined, the first and second compression pipes 23 are compressed. Each of the machines 10 and 11 branches into two suction branch pipes 23A and 23B. The oil return pipe 24 is provided with a decompression means 26 such as a capillary tube in the pipeline.

  Each suction branch pipe 23 </ b> A of the suction pipe 23 is connected to the high-pressure container 27 of the first and second compressors 10 and 11. Only the refrigerant sucked into the corresponding one of the compressors 10 and 11 flows through each intake branch pipe 23A. A predetermined amount of refrigerating machine oil is accommodated in each of the high-pressure containers 27 of the first and second compressors 10 and 11. The outdoor unit 3 includes a third compressor 30 and a fourth compressor 31 that are high-pressure shell type compressors, and has the same configuration as the outdoor unit 2. The outdoor unit 4 includes a fifth compressor 40 and a sixth compressor 41, which are high-pressure shell type compressors, and has the same configuration as the outdoor unit 2.

  Here, the refrigerator 1 is provided with a compressor oil leveling device 51 connected to each of the compressors 10, 11, 30, 31, 40, and 41. The compressor oil leveling device 51 includes a first oil leveling unit 52 built in the outdoor unit 2, a second oil leveling unit 53 built in the outdoor unit 3, and a third oil leveling unit built in the outdoor unit 4. The oil leveling units 52 to 54 are connected to the collecting gas pipe 5 and the collecting liquid pipe 6 via inter-unit oil leveling pipes 55.

  The first oil leveling unit 52 has a connecting pipe 62 connected to a predetermined height from the bottom of the high-pressure vessel 27 of the first compressor 10. This connection pipe 62 is connected to the inflow end of the gas-liquid separation means 63. The gas-liquid separation means 63 is configured to separate a fluid mixed with gas-liquid into gas and liquid using, for example, centrifugal force. In the gas-liquid separation means 63, an oil return pipe 64 is connected to a first outflow end from which liquid mainly flows out. The oil return pipe 64 is connected to the suction branch pipe 23A through which only the refrigerant sucked into the first compressor 10 flows after the capillary tube 65 as the first pressure reducing means is provided in the pipe line. . In FIG. 1, the accumulator 28 is provided in the pipe of the suction branch pipe 23 </ b> A, but may be connected to a pipe portion other than the accumulator 28. On the other hand, in the gas-liquid separation means 63, an oil equalizing pipe 66 is connected to a second outflow end from which mainly gas flows out. The oil equalizing pipe 66 is provided with a capillary tube 67 as a second pressure reducing means in the pipe line, and is connected to an oil equalizing collecting pipe 68 (oil equalizing pipe). The oil leveling collecting pipe 68 is connected to the inter-unit oil leveling pipe 55.

  A connection pipe 62 is connected to the second compressor 11 at a predetermined height from the bottom of the high-pressure vessel 27, and this connection pipe 62 is connected to the inflow end of the gas-liquid separation means 63. An oil return pipe 64 is connected to the first outflow end of the gas-liquid separation means 63. The oil return pipe 64 is provided with a capillary tube 65, and is connected to the accumulator 28 of the suction branch pipe 23B through which the refrigerant sucked only by the second compressor 11 passes. An oil leveling pipe 66 is connected to the second outflow end of the gas-liquid separation means 63. The oil leveling pipe 66 is connected to an oil leveling collecting pipe 68 after the capillary tube 67 is provided.

  Similarly, the second oil leveling unit 53 has gas-liquid separation means 63 connected to a predetermined height from the bottom of the high-pressure vessel 27 of the third compressor 30 by a connecting pipe 62. The oil return pipe 64 on the first outflow end side of the gas-liquid separation means 63 is connected to the suction branch pipe 23A of the third compressor 30 after the capillary tube 65 is provided. The oil leveling pipe 66 on the second outflow end side of the gas-liquid separation means 63 is connected to the oil leveling collecting pipe 68 after the capillary tube 67 is provided. Further, similarly, the fourth compressor 31 side has a gas-liquid separation means 63 connected to the fourth compressor 31 by a connecting pipe 62, an oil return pipe 64, an oil equalizing pipe 66, and capillary tubes 65 and 67. is doing. The oil return pipe 64 is connected to the suction branch pipe 23B of the fourth compressor 31. The oil leveling collecting pipe 68 is connected to the inter-unit oil leveling pipe 55.

  The third oil leveling unit 54 includes gas-liquid separation means 63 connected to the fifth compressor 40 via a connection pipe 62, an oil return pipe 64, an oil leveling pipe 66, and capillary tubes 65 and 67. The oil return pipe 64 is connected to the suction branch pipe 23 </ b> A of the fifth compressor 40. Furthermore, it has gas-liquid separation means 63 connected to the sixth compressor 41 by a connecting pipe 62, an oil return pipe 64, an oil equalizing pipe 66, and capillary tubes 65 and 67. The oil return pipe 64 is connected to the suction branch pipe 23B of the sixth compressor 41. The oil leveling collecting pipe 68 is connected to the inter-unit oil leveling pipe 55.

  The inter-unit oil leveling pipe 55 is branched into two branch pipes 55A and 55B after the oil leveling units 52 to 54 are connected, and the first branch pipe 55A is connected to the first check valve 70 (flow path switching). To the collective gas pipe 5 via the means). The connection point of the first branch pipe 55A is closer to the indoor unit 7 than the branch point where the collective gas pipe 5 branches to the gas pipe 5A. Similarly, the second branch pipe 55B is connected to the collecting liquid pipe 6 via the second check valve 71 (flow path switching means). The connection point of the second branch pipe 55B is closer to the indoor unit 7 than the branch point where the collecting liquid pipe 6 branches to the liquid pipe 6A. The first check valve 70 is opened when the pressure of the inter-unit oil leveling pipe 55 is higher than the pressure of the collective gas pipe 5, and is closed when the pressure of the inter-unit oil leveling pipe 55 is lower than the pressure of the collective gas pipe 5. It is configured. Similarly, the second check valve 71 is configured to open when the pressure of the inter-unit oil leveling pipe 55 is higher, and to close when the pressure of the inter-unit oil leveling pipe 55 is lower than the pressure of the collecting liquid pipe 6. Yes.

  The capillary tubes 65 and 67 are such that the pressure of the refrigerant or the refrigerating machine oil is lower than the internal pressure of the high-pressure vessel 27 of each compressor 10, 11, 30, 31, 40, 41 and the internal pressure of the gas-liquid separation means 63. The pressure of the refrigerant and the refrigerating machine oil is set to be higher than the internal pressure of the suction pipe 23 and the suction branch pipes 23A and 23B. Further, in the capillary tubes 65 and 67, the flow rate of the refrigerant flowing through the oil equalizing units 52, 53 and 54 is a predetermined ratio with respect to the flow rate of the refrigerant flowing through the main circuit passing through the indoor and outdoor heat exchangers 17 and 21. The channel resistance is set to be as follows. Further, when the capillary tube 65 and the capillary tube 67 are compared, the capillary tubes 65 and 67 control the flow rate passing through the oil return pipe 64 and the flow rate flowing into the oil equalizing collecting pipe 68 to control the compressors 10 and 11. , 30, 31, 40, 41 are set in advance so as to be held at predetermined levels. Therefore, the capillary tube 65 functions as a first flow rate adjusting unit, and the capillary tube 67 functions as a second flow rate adjusting unit.

  Further, the volume of the gas-liquid separation means 63 is not more than a predetermined volume with respect to the minimum required oil amount of each compressor 10, 11, 30, 31, 40, 41. More specifically, it is between the gas-liquid separation means volume range R1 shown in FIG. In this embodiment, the lower limit value of the gas-liquid separation means volume range R1 was a volume corresponding to 5% of the refrigerating machine oil. Further, the upper limit value of the gas-liquid separation means volume range R1 was a volume corresponding to 20% of the refrigerating machine oil. If the volume of the gas-liquid separation means 63 is less than the lower limit value, the liquid / gas separation performance is lowered, which is not preferable. Further, when the volume of the gas-liquid separation means 63 is less than the upper limit value, excess refrigeration oil stagnates in the gas-liquid separation means 63 and is necessary for the operation of the compressors 10, 11, 30, 31, 40, 41. It is not preferable because there is not enough freezer oil.

Next, the operation of this embodiment will be described.
First, the flow of the refrigerant when the three outdoor units 2 to 4 are simultaneously operated to perform the cooling operation and the heating operation will be described in order. In addition, cooling operation is performed while stopping one or two outdoor units 2 to 4 or only one of the compressors 10, 11, 30, 31, 40, and 41 of any one of the outdoor units 2 to 4. Or heating operation is also possible.

  During the cooling operation, the four-way valves 16 of the outdoor units 2 to 4 are switched to connect the first port 16A and the second port 16B, and connect the third port 16C and the fourth port 16D. The high-pressure gas refrigerant discharged from the compressors 10, 11, 30, 31, 40, and 41 is separated from the refrigeration oil mixed in the gas refrigerant by the oil separator 15, and then the outdoor heat exchanger from the four-way valve 16. 17 leads. In the outdoor heat exchanger 17, the gas refrigerant is liquefied by heat exchange to form a high-pressure liquid refrigerant. The liquid refrigerant joins in the collecting liquid pipe 6 and is guided to the indoor unit 7 in operation. In the indoor unit 7, the liquid refrigerant is decompressed by the indoor-side decompression device 20 and then flows into the indoor heat exchanger 21. In the indoor heat exchanger 21, the low-pressure liquid refrigerant is vaporized by heat exchange to form a low-pressure gas refrigerant. At this time, the indoor air is cooled by taking the heat of vaporization from the surrounding air. The low-pressure gas refrigerant is recovered from the indoor heat exchanger 21 through the collective gas pipe 5 while branching to the outdoor units 2 to 4. In each outdoor unit 2, it is led from the four-way valve 16 to the suction pipe 23 and sucked into the compressors 10, 11, 30, 31, 40, 41 from the suction branch pipes 23A, 23B. Then, it is pressurized again and discharged to the discharge pipe 14.

  When the refrigerator 1 performs a heating operation, the four-way valves 16 of the outdoor units 2 to 4 are switched to connect the first port 16A and the fourth port 16D, and the second port 16B and the third port 16C are connected. Connecting. The high-pressure gas refrigerant discharged from each of the compressors 10, 11, 30, 31, 40, 41 merges from the four-way valve 16 through the collecting gas pipe 5 and is introduced to the indoor heat exchanger 21 of the indoor unit 7 in operation. It is burned. In the indoor heat exchanger 21, the gas refrigerant is liquefied to form a liquid refrigerant, and the room is heated by the condensation heat released at this time. The liquid refrigerant is depressurized by the indoor decompression device 20 and flows through the collecting liquid pipe 6 as an intermediate pressure liquid refrigerant, and is branched and collected into the outdoor units 2 to 4, and the outdoor decompression device 18 and the outdoor heat exchanger 17 are collected. It passes through and becomes a low-pressure gas refrigerant. The gas refrigerant is sucked from the four-way valve 16 through the suction pipe 23 into the compressors 10, 11, 30, 31, 40, 41 through the suction branch pipes 23A, 23B. Then, it is pressurized again and discharged to the discharge pipe 14.

  While the refrigerator 1 is operated while circulating the refrigerant in this way, each outdoor unit 2 is maintained by the compressor oil leveling device 51 while maintaining the operating state of each compressor 10, 11, 30, 31, 40, 41. The equalization of the refrigerating machine oil between the two compressors 10, 11, 30, 31, 40, and 41 in 4 and the equalization of the refrigerating machine oil between the outdoor units 2 to 4 are performed.

  For example, when the amount of refrigerating machine oil in the high-pressure vessel 27 of the first compressor 10 is large and the oil level is at a position higher than the connection position of the connection pipe 62 (hereinafter, it is assumed that the refrigerating machine oil is excessive in this state. Only the refrigerating machine oil flows from the connecting pipe 62 into the inflow end 63A of the gas-liquid separating means 63. In this case, as shown in FIG. 3, the gas-liquid separation means 63 is filled with the refrigerating machine oil flowing out from the high-pressure vessel 27 of the first compressor 10, and the oil is discharged from the first outflow end 63B and the second outflow end 63C, respectively. The refrigeration oil flows out to the return pipe 64 and the oil equalizing pipe 66. The refrigeration oil that has flowed out to the oil return pipe 64 returns only to the first compressor 10 that is the original compressor. The refrigerating machine oil that has flowed out into the oil equalizing pipe 66 flows into the inter-unit oil equalizing pipe 55 through the oil equalizing collecting pipe 68. Since the gas-liquid separation means 63 side is at a high pressure by the capillary tube 67, it does not flow backward from the oil equalizing collecting pipe 68 to the gas-liquid separation means 63 on the second compressor 11 side. Similarly, there is no backflow from the inter-unit oil leveling pipe 55 to the second and third oil leveling units 53, 54. The refrigerating machine oil that has flowed into the inter-unit oil leveling pipe 55 flows out to the collecting gas pipe 5 or the collecting liquid pipe 6 through one of the first and second check valves 70 and 71.

  As shown in FIG. 4, when the refrigerator 1 is in the cooling operation, a low-pressure gas refrigerant flows through the collective gas pipe 5, and the internal pressure of the collective gas pipe 5 is relative to the internal pressure of the inter-unit oil leveling pipe 55. The first check valve 70 is open. Therefore, the refrigeration oil flows out to the collecting gas pipe 5 through the first check valve 70. On the other hand, since the high pressure liquid refrigerant flows through the collecting liquid pipe 6 and the internal pressure of the collecting liquid pipe 6 is relatively higher than the internal pressure of the inter-unit oil leveling pipe 55, the second check valve 71 is closed, Refrigerator oil does not flow out. The refrigerating machine oil that has flowed out into the collective gas pipe 5 is mixed into the low-pressure gas refrigerant and flows into the outdoor units 2 to 4 from the gas pipe 5A. In each of the outdoor units 2 to 4, it flows from the four-way valve 16 through the suction pipe 23 and is sucked into the compressors 10, 11, 30, 31, 40, and 41. As a result, the refrigeration oil of the compressor (in this case, the first compressor 10) with excessive refrigeration oil gradually decreases, and the refrigeration oil of other compressors gradually increases.

  As shown in FIG. 5, when the refrigerator 1 is in the heating operation, since the high-pressure gas refrigerant flows through the collective gas pipe 5, the internal pressure of the collective gas pipe 5 is higher than the internal pressure of the inter-unit oil leveling pipe 55. Is relatively high, and the first check valve 70 is closed. Therefore, the refrigeration oil does not flow out to the collecting gas pipe 5. On the other hand, since the intermediate pressure liquid refrigerant passing through the indoor unit 7 flows through the collecting liquid pipe 6 and the internal pressure of the collecting liquid pipe 6 is relatively lower than the internal pressure of the inter-unit oil leveling pipe 55, the second check Valve 71 opens. Therefore, the refrigeration oil flows out to the collecting liquid pipe 6. The refrigerating machine oil that has flowed out into the collecting liquid pipe 6 is mixed into the intermediate-pressure liquid refrigerant and flows into the outdoor units 2 to 4 from the liquid pipe 6A. In each of the outdoor units 2 to 4, it flows from the four-way valve 16 through the suction pipe 23 and is sucked into the compressors 10, 11, 30, 31, 40, and 41. As a result, the refrigeration oil of the excessive compressor (in this case, the first compressor 10) of the refrigeration oil gradually decreases, and the refrigeration oil of the other compressors gradually increases.

  Further, as shown in FIG. 6, for example, when the refrigeration oil in the high-pressure vessel 27 of the first compressor 10 is small and the oil level is lower than the connection position of the connection pipe 62 (hereinafter, this state is referred to as When the refrigerating machine oil is equal to or less than a predetermined amount), the gas refrigerant and the oil mist of the refrigerating machine oil mixed in the gas refrigerant flow into the gas-liquid separation means 63 through the connection pipe 62. The gas-liquid separation means 63 separates the oil mist and the gas refrigerant. The oil mist flows out from the first outflow end 63B to the oil return pipe 64, passes through the oil return pipe 64, and returns to the first compressor 10 that is the original compressor from the suction branch pipe 23A. Therefore, the refrigerating machine oil mixed in the gas refrigerant in the first compressor 10 is recovered by the first compressor 10 itself. This prevents the refrigeration oil from flowing out of the first compressor 10 and prevents the oil level in the high-pressure vessel 27 from being lowered. The refrigerant separated by the gas-liquid separation means 63 flows out from the second outflow end 63C through the oil equalizing collecting pipe 68 to the inter-unit oil equalizing pipe 55. This gas refrigerant flows into the collective gas pipe 5 through the first check valve 70 during the cooling operation, and passes through the second check valve 71 during the heating operation, in the same manner as the above-described excessive refrigeration oil. Then, it flows into the collecting liquid pipe 6 and is sucked into the compressors 10, 11, 30, 31, 40, 41.

  Similarly, with respect to the other compressors 11, 20, 21, 30, 31 as well, when the amount of refrigeration oil is larger than a predetermined amount, that is, when the refrigeration oil is excessive, the collecting gas pipe 5 or It is distributed from the collecting liquid pipe 6 to the compressors 10, 11, 30, 31, 40, 41. On the other hand, when the refrigerating machine oil is less than or equal to the predetermined amount, it flows back to the original compressor only through the oil return pipe 64. Therefore, in the process of operating the refrigerator 1, the refrigerator oil of the compressors 11, 20, 21, 30, and 31 is equalized.

  In this embodiment, in a configuration having a plurality of outdoor units 2 to 3, a compressor oil leveling device 51 is provided, and surplus refrigeration oil is supplied to the plurality of compressors 10 through the collective gas pipe 5 or the collective liquid pipe 6. , 11, 30, 31, 40, 41, the compressors 10, 11, 30, 31, 40, 41 are not stopped without stopping the compressors 10, 11, 30, 31, 40, 41. Refrigerator oil can be equalized. Since the inter-unit oil leveling pipe 55 of the compressor oil leveling device 51 is provided with the first and second check valves 70 and 71, the pressure is relatively low in the collective gas pipe 5 or the collective liquid pipe 6, and Refrigerating machine oil can be caused to flow into the piping through which the refrigerant returns to the outdoor units 2 to 4 flows. Therefore, the refrigeration oil can be quickly distributed to the compressors 10, 11, 30, 31, 40, 41 without passing through the indoor unit 7. Further, the inter-unit oil leveling pipe 55 is formed from the gas pipe 5A and the liquid pipe 6A which are pipes branched from the collective gas pipe 5 and the collective liquid pipe 6 toward the outdoor unit 4 disposed closest to the indoor unit 7. Since it is connected to the indoor unit 7 side, it is possible to distribute the refrigerating machine oil of all the compressors 10, 11, 30, 31, 40, 41. If the inter-unit oil leveling pipe 55 is connected in the vicinity of the gas pipe 5A and the liquid pipe 6A, the path through which the refrigerating machine oil flows can be shortened.

The present invention is not limited to the above embodiment and can be widely applied.
For example, as shown in FIG. 7, the first and second check valves 70 and 71 may be built in the outdoor unit 4 closest to the indoor unit 7. In this case, a part of the collecting gas pipe 5 and the collecting liquid pipe 6 are drawn into the outdoor unit 4, and the inter-unit oil leveling pipe 55 is also drawn into the outdoor unit 4. In the outdoor unit 4, the first branch pipe 55 </ b> A is connected to the drawn-in portion 75 of the collecting gas pipe 5 via the first check valve 70, and the second branch pipe 55 </ b> B connects the second check valve 71. To the drawn-in portion 76 of the collecting liquid pipe 6. In general, the connection between the collecting gas pipe 5 and the collecting liquid pipe 6 and the outdoor unit 4 is performed at the site where the refrigerator 1 is actually installed. Therefore, in the form shown in FIG. 1, the collecting gas pipe 5 and the collecting liquid pipe are used. 6 and branch pipes 55A and 55B are connected on site. Since the first and second branch pipes 55A and 55B are provided with the first and second check valves 70 and 71, when these branch pipes 55A and 55B are connected by welding, the first and second It is necessary to perform construction on site while taking into consideration the effect of heat on the two check valves 70 and 71. In the form shown in FIG. 7, the first and second branch pipes 55A and 55B can be connected to the portions 75 and 76 drawn in advance in the manufacturing stage. Then, it is only necessary to weld the remaining collecting gas pipe 5 and collecting liquid pipe 6, and the work at the site becomes easy.

  The compressor oil leveling device 51 may use an on-off valve as a flow path switching means instead of a check valve. As shown in FIG. 8, the branch pipe 55 </ b> A of the inter-unit oil leveling pipe 55 is connected to the collecting gas pipe 5 via the first on-off valve 80, and the branch pipe 55 </ b> B is connected to the collecting liquid via the second on-off valve 81. Connected to the tube 6. The first and second on-off valves 80 and 81 are controlled to be opened and closed in accordance with the operation mode of the refrigerator 1 by a control device (not shown). During the cooling operation, the first on-off valve 80 is opened and the second on-off valve 81 is closed. The refrigerating machine oil in the inter-unit oil leveling pipe 55 is distributed from the collecting gas pipe 5 to the compressors 10, 11, 30, 31, 40, 41. During the heating operation, the first on-off valve 80 is closed and the second on-off valve 81 is opened. The refrigerating machine oil in the inter-unit oil leveling pipe 55 is distributed from the collecting liquid pipe 6 to the compressors 10, 11, 30, 31, 40 and 41. In the form of FIG. 7, the first and second check valves 70 and 71 can be replaced with the first and second on-off valves 80 and 81.

Moreover, the compressor 10, 11, 30, 31, 40, 41 for every outdoor unit 2-4 is not limited to two each. One may be sufficient and three or more may be sufficient.
The capacity of the gas-liquid separation means 63 can select an optimum volume depending on the refrigerator, and if it is less than the minimum oil amount necessary for the operation of the compressor, it is outside the gas-liquid separation means volume range R1. But it ’s okay.
The first and second decompression means may be expansion valves, on-off valves, or other decompression means instead of the capillary tubes 65 and 67.

It is a figure which shows the structure of the refrigerator which concerns on embodiment of this invention, and a compressor oil equalizing apparatus. It is a figure which shows the range of the volume of a gas-liquid separation means. It is a figure explaining the effect | action of the gas-liquid separation means of a compressor oil equalizing apparatus. It is a figure which shows typically a mode that refrigeration oil is distributed to several compressors through an aggregate gas pipe at the time of air_conditionaing | cooling operation. It is a figure showing typically signs that refrigeration oil is distributed to a plurality of compressors through a collecting liquid pipe at the time of heating operation. It is a figure explaining the effect | action of the gas-liquid separation means of a compressor oil equalizing apparatus. It is the figure which provided the flow-path switching means in the outdoor unit. It is a figure which shows the other form of a flow-path switching means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerator 2, 3, 4 Outdoor unit 5 Collected gas pipe 6 Collected liquid pipe 7 Outdoor unit 10 1st compressor 11 2nd compressor 23 Suction piping 27 High pressure vessel 30 3rd compressor 31 4th compressor 40 5th Compressor 41 Sixth compressor 51 Compressor oil leveling device 55 Unit oil leveling tube 55A First branch pipe 55B Second branch pipe 63 Gas-liquid separation means 63B First outflow end 63C Second outflow end 65 Capillary tube (first One decompression means)
66 Oil equalizing pipe 66 Capillary tube (second decompression means)
70, 71 Check valve (first flow path switching means, second flow path switching means)
75,76 Retracted part 80,81 On-off valve (first flow path switching means, second flow path switching means)

Claims (6)

A plurality of outdoor units and indoor units are connected by a collecting gas pipe and a collecting liquid pipe, and the refrigerant is circulated by sucking the refrigerant from the suction pipe into the compressor mounted on the outdoor unit, pressurizing it, and discharging it. A compressor oil leveling device for keeping the refrigerating machine oil evenly between the compressors,
A gas-liquid separation means connected to a high-pressure vessel of the compressor, wherein the gas-liquid separation means mainly includes a first outflow end through which refrigeration oil flows out; Is provided with a second outflow end for flowing out the refrigerating machine oil, and the first outflow end supplies the refrigerant to the compressor in the suction pipe via the first pressure reducing means An oil equalizing pipe is connected to the second outflow end, and the oil equalizing pipe is connected to the inter-unit oil equalizing pipe after the second pressure reducing means is provided in the path, The inter-unit oil equalizing pipe is branched into two connecting pipes after the oil equalizing pipes of the plurality of outdoor units are connected, and the first branch pipe is connected to the collecting gas pipe via the first flow path switching means. And the second branch pipe connects the second flow path switching means. To compressor oil equalizing system, characterized in that it is connected to the collecting liquid pipe.   The inter-unit oil equalizing pipe is connected to the collecting gas pipe and the collecting liquid pipe on the indoor unit side from a branching point where the collecting gas pipe and the collecting liquid pipe branch toward the outdoor unit. The compressor oil equalizing device according to claim 1.   The first flow path switching means is a check valve that opens only when the internal pressure of the inter-unit oil leveling pipe is higher than the internal pressure of the collective gas pipe, and the second flow path switching means is the The compressor oil leveling device according to claim 1 or 2, wherein the check valve is opened only when an internal pressure is higher than an internal pressure of the collecting liquid pipe.   The said 1st flow-path switching means and the 2nd flow-path switching means consist of an opening-and-closing valve by which opening / closing control was carried out so that the other might close, when one was opened. Compressor oil leveling equipment.   The said 1st, 2nd flow-path switching means and said 1st, 2nd branch pipe are incorporated in the said outdoor unit most arrange | positioned at the said indoor unit side. The compressor oil leveling device. 5. The compressor oil leveling device according to claim 1, a plurality of the outdoor units in which the compressor oil leveling device is connected to the compression, the aggregate gas pipe, and the aggregate A refrigerator comprising a liquid pipe and the indoor unit.

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